An antenna arrangement has been disclosed, for example, in DE 201 11 229 U 1. This prior publication describes an antenna arrangement for motor vehicles which has a chassis. A printed circuit board is arranged above the chassis in order to accommodate circuit components. One or more vertically projecting antenna elements, which is or are at least partially flat, is or are provided vertically with respect to the printed circuit board. The printed circuit board is aligned essentially horizontally to receive different services or for different frequencies in the mobile radio band.
The entire antenna arrangement is covered by a shroud which may have a shape similar to a fin. Antennas such as these are normally fitted to the motor vehicle bodywork plate, for example at the junction between the motor vehicle roof and the rear windshield.
A multiple frequency antenna arrangement in particular for motor vehicles having a corresponding shroud has been disclosed in EP 0 862 239 A1. By way of example, two printed circuit boards, which are aligned vertically and are offset laterally transversely with respect to the vertical plane are provided in the housing, which is in the form of a shroud, for accommodation of the electronic components. A connecting adapter is provided at the upper end of the housing, that is to say at the uppermost point of the shroud, in order to make it possible to attach an antenna in the form of a whip antenna there.
An antenna which can preferably be used for cars has likewise been disclosed in DE 694 19 080 C2. This antenna also has a housing in the form of a shroud, at whose uppermost projection point a connecting point is provided for a whip antenna. One or more printed circuit board elements, which are aligned vertically or horizontally, can be arranged within the antenna housing. In one arrangement, these printed circuit board elements are likewise arranged parallel to one another and are arranged alongside one another transversely with respect to the plane of the printed circuit board, to be precise aligned transversely with respect to the vehicle longitudinal axis. However, they may also likewise be arranged with a lateral offset parallel to one another, to be precise aligned longitudinally with respect to the vehicle axis.
Furthermore, antenna arrangements are also known in which the printed circuit board is provided with electronic circuitry components, filter circuits etc. formed on a more or less horizontal chassis. The antenna elements are once again positioned vertically at right angles to this, in the vertical direction. These antenna elements may, for example, not only be composed of metallically conductive self-supporting antenna element devices but, for example, may likewise once again be formed from a printed circuit board element, that is to say in general from a dielectric material, on which metalized surfaces are provided in order to form the antenna elements.
If the aim is now to receive in only one frequency band range, then one antenna element is sufficient. If the aim is to provide two or more services or one service more than once, or if the aim is, for example, to communicate in various frequency bands in the mobile radio range, then, of course, two or more antenna elements are provided, which are offset with respect to one another or are flat.
The exemplary illustrative non-limiting technology herein provides a further improved antenna arrangement which, in principle, has good antenna characteristics with reduced production and material costs overall.
It has now surprisingly been found that there is no need for a horizontal, separate printed circuit board with the matching circuit required for the antenna. Specifically, according to the exemplary illustrative non-limiting technology herein, one or more printed circuit boards are used, which are preferably aligned alongside one another vertically on a common plane and are provided adjacent to the at least one antenna element. The appropriate components for a radio-frequency circuit, which may possibly be provided, are, for example, accommodated on this vertically aligned printed circuit board.
According to the exemplary illustrative non-limiting technology herein, the use of a vertically aligned printed circuit board once again allows the overall design of a corresponding antenna arrangement to be simplified considerably. One surprising feature of this illustrative non-limiting implementation is that the vertically aligned printed circuit board, which rests on the antenna element at the side, does not influence the antenna polar diagram disadvantageously in the manner which would intrinsically be expected.
One exemplary illustrative non-limiting implementation provides at least one antenna element arrangement that is not provided above the printed circuit boards but at the side, alongside this at least one printed circuit board. This prevents any disadvantageous influence on the polar diagram characteristic. This is also particularly surprising, and is not obvious, because an antenna such as this with as broad a bandwidth as possible for the mobile radio field is designed for wavelengths in the range from around 15 cm to 30 cm, so that the size of the vertically arranged printed circuit board is in the range that is relevant for these wavelengths.
Furthermore, in one exemplary illustrative non-limiting implementation, it is possible to provide only a single printed circuit board on which not only the radio-frequency circuit which may possibly be provided is accommodated but on which, for example, flat conductive sections can then also be formed on other section areas, forming the relevant antenna element, in this case, widely differing geometric shapes can be used to form the antenna element. For example, whip antenna implementations may have a vertically running, flat antenna section, which merges at the top into, for example, an antenna section at the rear.
If, by way of example, a further antenna element is intended to be provided for a second frequency band for the mobile radio area, or in order to provide further services, then this likewise can preferably be provided as a flat antenna element in an area of the printed circuit board that is offset with respect to the first antenna element. However, in precisely the same way, it is also possible to use a further printed circuit board element, which is located on the same plane as the first printed circuit board element or, for example, is offset laterally parallel to it, in order to accommodate the at least one further antenna element here.
Thus, overall, the antenna elements and the radio-frequency circuit which may possibly be provided can be accommodated in a preferred manner on a single, common printed circuit board arrangement.
In one exemplary illustrative non-limiting implementation, a cap, which is used for mechanical retention, is required only for installation on the motor vehicle and for mechanical anchoring of the printed circuit board and of the antenna elements located on it.